Cleaning up django settings files

[twinkarma]

A lot of changes has been made to how the app (django settings) is configured and now we've moved to mainly use environment variables rather putting values settings files themselves. It would be good to check whether some values are now redundant e.g.

• database settings in deployment.py?
• test.py is now just blank (but maybe useful to just leave it in case something needs to be added in the future)
• Can we use the same settings for docker and non-docker?
• What else?